Can You Solve This Water Puzzle? It Has Challenged Many People

At first glance, the puzzle appears surprisingly simple. Four identical drinking glasses are placed side by side, each seemingly filled to exactly the same water level. Inside each glass rests a different object: a small paperclip, a baseball, an eraser, and a wristwatch.

The challenge asks only one question: Which glass contains the greatest amount of water? Because every glass appears equally full, many people instinctively assume they all contain the same amount of water.